Lever escapement



G. GALLAY.

LEVER ESOAPEMENT;

APPLICATION mm m. s. 1920.

Patented Oct. 31, 1922.-

Patented Oct. 31, 1922.

UNITED STATES GEORGES GALLAY, OF LE SENTIER, SWITZERLAND.

LEVER ESCAPEMENT.

Application filed January 5, 1920.

To all w ham it may concern Be it known that I, GEORGES GALLAY, citizen of the Swiss Republic, residing at Le Sentier, Canton of Vaud, Switzerland, hai e invented certain new and useful Lever capements, of which the following is a specitication.

In lever escapements hitherto mamlfactured. and which are said to be normal the pivoting center of the lever or anchor-shaped piece is at the intersection of perpendicular lines raised from each of the operating rays at the point where said rays cut the original circumference, so that in any case the ratio:

cos a is to be found, in which ratio Dzdistance from the centers, R the ray of the original circumference, z=the angle between the center-to-cent er line and the operating ray taken into account.

In some escapements, the aforesaid ratio varies for one of the angles owing to the angle including the number of half teeth contained between the pallets, i. e. determined by the two operating rays, not being equal on each side of the center-to-center line. As a matter of fact, it is customary, in making escapements with equidlstant levers, to add, to one half of the insertion angle, on. the side of the inlet pallet, an angle equalling one half of the angle made by the wheel at each oscillatlon of the anchor, which angle is subtracted from that half obtained on the side of the outlet pallet. The result is that, as regards the operat ng ray pointing to said pallet, viz: forming with the center-to-center line, the smallest of the two angles. the hereinbefore men is correct. For the large angle, the ratio obtained is R as? but it should. be noticed that said angle is larger than one half of the angle between the operating rays.

Serial No. 349,550.

In all these normal lever escapements, the angles formed by the stop face of the pallet and the slope of the pallet face are different foreach pallet. The angle of the inlet pallet ]s more acute than that of the outlet pal let. The consequence is that the outlet pallet is very sharp, hence very brittle. On the other land, the necessity of having two kinds of pallets, complicates the jewelsetting of the levers and errors often occur, whlch errors cause the loss of the anchor.

The present invention,--which aims at obviating the aforesaid defectsrelates to a lever escapement, the various parts whereof are so dimensioned as to secure the interchangeability of the pallets. The full lines of the single figure of drawings represents the escapement wheel bearing against the entrance impulse tooth and the dotted lines in the drawin represents the position of said wheel and pallet when the said wheel bears against the outlet impulse tooth.

The point 0 represents the position of the center of rotation of the anchor in the usual escapement as heretofore constructed; this point 0 is, as already known, the point of intersection of the tangent lines A 0 B 0 of the wheel at points A and B. 0 O is the bisecting line of the angle A O B. There is no geometrical formula for finding the point The point 0 is found as heretofore and the location of the point 0 was the result of experimental researches.

The advantages of such construction are Ol')"l0USZ 'Errors in jewel-setting are done away with and the pallets are cheaper, as there is practically no waste of outlet pallets; besides, since the pallets are interchangeable the stocks of pallets at the watch-jobbers are reduced by half.

To obtain such pallets, one may, for ex ample, assume the distance between the pivoting centers of the escape wheel and of the anchor to be longer than the original ray of the lever Wheel divided by the cosine of one half of the angle between the two operating rays.

In the drawings are shown, by way of example, an escapement the wheel of which has fifteen teeth, two and a half of said teeth being engaged in the anchor.

In the escapement shown the center of the escape wheel is at O and that of the anchor pivot at 0 The operating rays are designated by GA and OB. The latter do not includcbetwecn themselves an integer of half-teeth. The sum total of the angles 0. and B is but 59 38, whereas, in a normal escapement, said angle, in the case of like dimensions of construction, should be (30 and should include exactly live half-teeth. The rest of the escapement is constructed in accordance with the rules usually admitted for normal escapements with the difference that the length 0 O is larger than COS or The result is that the straight lines connecting the stop or rest points with the. pivoting centers of the anchor are not tangent to the original circumference of the escape wheel. and therefore are not perpendicular to the operating rays 0A and OD. l.herefore, on the one hand, with reference-to the inlet pallet, the angle formed by the stop or rest plan and the slope is wider than in ordinary constructions and, on the other hand, with reference to the outlet pallet, the angle constituted by the same parts, is much more acute.

In an ordinary construction of escapement the pivoting center of the anchor is determined by the intersection of the perpendicu lar lines raised on each side, from the operating rays. This construction, besides, renders it possible to notice that said operating rays are not equally dist-ant from the center-to-center line. Moreover, these rays do not enclose a full member of half-teeth. lVith such improvements, practically equal drops or falls may be secured, which otherwise could not be obtained. In such construction the distance of the centers is equal to the ray of the original circumference, i. e. to that which passes the foren'iost point of the tooth, divided by the cosine of the angle between the operating ray and the centerto-center line. It is easy to notice that, in the escapement made according to the invention, (and shown in the drawings) the distance O z: I) is longer than in a normal escapement and this is true for all escapements constructed in view of using interchangeable pallets, that pallets which may practically differ from each other, beyond the usually admitted tolerance of a few minutes, but which, theoretically, are identical.

In normal lever escapements, the anchor whereof encompasses two and a half teeth. of a fifteen tooth wheel the'ratio is:

=2 cos 0 178206;

this ratio becomes 1.81.262 should the wheel bear eighteen teeth. In an escapement according to the invention, the aforesaid ratio is 1.65 for the fifteen tooth wheel and 1.70 for the eighteen tooth wheel.

I claim as my invention:

1. A lever escapement having interchangeable pallets in the plane of the lever. an escape wheel so situated relative to the lever that the distance between their pivotalcenters is greater than the original ray of the wheel divided by the cosine of one half the angle included. between the two operating rays.

2. A lever escapeu'lent mechanism coniprising an escape wheel and an anchor, said. anchor having interchr-mgeable pallets, the characteristic features being that the distance between the pivoting centers of the escape wheel and the anchor is longer than the original ray of the lever wheel divided by the cosine of one half of the angle included between the two operating rays.

A lever escapement mechanism comprising an escape wheel and an anchor said anchor having interchangeable pallets, the characteristic feature being that the distance between the pivoting centers of the escape wheel and. the anchor is longer than the original ray of the lever wheel divided by the cosine of one halfof the angle inserted by the two operating rays, the number of half-teeth included between the pallets expressed by being an integer and a fraction.

4:. Ar lever escapement mechanism comprising an escape wheel and an anchor, said anchor having interchangeal'ile pallets, the characteristic feature being that the distance between the pivoting centers of the escape wheel andthe anchor is longer than the original ray of the lever wheel divided by the cosine of one half of the angle inserted by the two operating rays. thelnaxr mum of the ratio being approximately 1.65 for a fifteen tooth wheel and for an 18 tooth wheel approximately 1.70.

In witness whereof I have hereunto set my hand in the presence of two witnesses.

GEORGES GALLAY. lVitnesses LOUIS H. h lnnirnn, J. LUILLONG.

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